The invention relates to a device for depositing synthetic fibers to form a non-woven web. In the production of spun-bond non-woven webs, freshly spun synthetic fibers are usually drawn off by means of a take-off nozzle of a spinneret and conveyed for being stacked on a depositing belt. The processes of guiding and conveying the fibers are brought about by means of an air stream of the take-off nozzle, which air stream is absorbed and discharged by exhaust equipment disposed below the depositing belt. The fibers accumulating on the surface of the depositing belt result in a non-woven web, which is conveyed continuously by the depositing belt. The formation of the non-woven web depends on the impingement of the fibers on the depositing belt and the belt speed. A change in the airflow can influence the impingement of the fibers, in particular.
Thus, for example, DE 37 40 893 A1 discloses a device for depositing synthetic fibers to form a non-woven web, in which device a plurality of mobile retaining flaps is disposed in a guide duct arranged upstream of the depositing belt in order to influence firstly the airflow of the take-off nozzle and secondly the airflow when the fibers impinge on the depositing belt. Thus the guide duct comprises, on each of its ends that face the depositing belt, a pivoting retaining flap that can be held at various angles of incidence relative to the depositing belt.
However, the disadvantage of the device disclosed is that slots are formed between the ends of the guide duct and the depositing belt. Such slots result in the exhaust equipment sucking in a substantial portion of the ambient air together with the supplied air stream. This results in increased air consumption and, in particular, a direct influence of the fiber depositing for forming the non-woven web. There exists the risk of obtaining so-called drifts in the non-woven web.
U.S. Pat. No. 6,379,136 discloses a device for depositing synthetic fibers to form a non-woven web, in which device the depositing area of the fibers at the end of the guide duct is sealed from the ambience by sealing rollers. However, the disadvantage of this device is that the fibers can only be stacked in a depositing area, which is kept constant. It is not possible to change the depositing area on the depositing belt.
It is now an object of the invention to further improve a device of the generic kind for depositing synthetic fibers to form a non-woven web such that the depositing of the fibers can be controlled with the maximum flexibility possible and without substantial external influences.
Another aim of the invention is to provide a device for depositing synthetic fibers to form a non-woven web with which device it is possible to produce non-woven webs having reproducible non-woven web qualities.